JPH06307240A - Exhaust pipe structure - Google Patents

Abstract

PURPOSE:To make the slide resistance of the support portion of a pipe that conducts heat extension/contraction due to the effect of exhaust heat, small and at the same time improve durability and realize cost reduction. CONSTITUTION:Inside ball support grooves 4 are provided in recess at diametric symmetry positions on the outer periphery surface of the rear end portion of an inner pipe 1 passing exhaust, and on the inner periphery surface of the inside cylindrical portion 2b of a rear joint pipe 2 formed so as to surround outwardly the rear end portion of the inner pipe 1, outside ball support grooves 6 to oppose the inside ball support grooves 4 are provided in recess, and balls 5 are interposingly provided between both ball support grooves 4, 6 that a in the connection state of both pipes, and the rear end portion of the inner pipe 1 is supported by means of the rear joint pipe 2. As a result, when the inner pipe 1 is thermally extended/contracted, its relative displacement with the rear joint pipe 2 is absorbed by means of the rolling of the balls 5, so resistance at the time of displacement can be reduced, and at the same time due to simple structure that does not require welding, durability is improved, and inexpensiveness can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust pipe structure, and more particularly to an exhaust pipe structure for releasing a displacement of a pipe for passing exhaust gas during thermal expansion and contraction.

[0002]

2. Description of the Related Art In recent years, an exhaust silencer in an exhaust pipe structure of an internal combustion engine is made of a synthetic resin material having excellent corrosion resistance and sound insulation as disclosed in, for example, Japanese Utility Model Laid-Open No. 3-63715. There are an outer shell as an outer plate member, an inner pipe that requires heat resistance formed of a metal material and a combination of both, and a combination of both formed of a synthetic resin material.

Among the conventional exhaust silencers as described above, there is one shown in FIG. The exhaust silencer shown in FIG. 4 has an outer shell 2 made of synthetic resin that defines an expansion chamber.
1 and a metal inner pipe 22 penetrating an intermediate portion of the outer shell 21. The left end of the inner pipe 22 in the drawing is connected to the engine via a front pipe (not shown).

The outer shell 21 is composed of an upper outer plate member 23 and a lower outer plate member 24, which are formed by vertically dividing a hollow casing into two parts. The outer shell member 23 and the outer shell member 24 form an intermediate portion of the inner pipe 22. The upper part and the rear end part are sandwiched from above and below respectively. Outer shell 21
A front boss portion 21a and a rear boss portion 21b, which are formed in a state where the outer shell members 23 and 24 are overlapped with each other to form the outer shell 21, are provided on the respective wall portions at both ends of the inner pipe 22 in the penetration direction. .

The mating portions 23a and 24a of the outer plate members 23 and 24 facing each other are adhered and fixed to each other, and the front joint pipe 25 and the rear joint pipe 26 are respectively attached to the front boss portion 21a and the rear boss portion 21b. Are fitted and the outer plate members 23 and 24 are joined together. A glass wool mat 27 having a predetermined thickness is attached to the inner surfaces of the outer plate members 23 and 24.

In the exhaust silencer as described above, the inner pipe 22 made of metal expands and contracts due to exhaust heat, but the outer shell 21 made of synthetic resin protected by the glass wool mat 27 does not expand and contract between them. It is necessary to absorb the resulting heat expansion and contraction.

In the above-mentioned conventional example, the middle portion of the inner pipe 22 is fixed to the front boss portion 21a, and the inner peripheral surface of the rear end portion of the rear joint pipe 26 is made of a stainless mesh as shown in FIG. The contact ring 28 is fixed. This sliding contact ring 28 allows the inner pipe 22
The inner pipe 22 that slidably supports the rear end portion thereof and thermally expands and contracts in the direction of arrow C in FIG. 5 under the influence of exhaust heat.
The displacement of the rear end of the rear is released.

However, not only is the sliding contact ring 28 used in the above structure relatively expensive due to the mesh structure made of stainless steel wire, but also the fixing of the sliding contact ring 28 to the inner peripheral surface of the joint pipe 26. If spot welding is performed, durability may be deteriorated, and further, sliding resistance is large.

[0009]

In view of the above problems of the prior art, the main object of the present invention is to reduce the sliding resistance of the supporting portion of the pipe which expands and contracts thermally due to the influence of exhaust heat and to improve the durability. It is to provide an exhaust pipe structure capable of improving the cost and reducing the cost.

[0010]

According to the present invention, such an object is formed by surrounding one end of both pipes connected to each other and surrounding the other end. A rolling element is interposed between the outer circumferential surface of the portion and the inner circumferential surface of the other end, and at least one of the both ends is guided so that the rolling element can be displaced in the axial direction of the both ends. This is achieved by providing an exhaust pipe structure characterized in that rolling element guide means is provided on either one of them.

[0011]

With this configuration, when the pipe thermally expands and contracts under the influence of the exhaust heat, the ends of the pipe are displaced in the axial direction thereof, but the rolling elements interposed at the connecting ends of both pipes. Are guided so that they can be displaced in the axial direction, and the rolling of the rolling elements can minimize the resistance at the time of relative displacement between the two pipes. Further, since one pipe can be supported displaceably via the rolling elements, it is not necessary to fix the sliding contact ring by spot welding or the like which affects durability, and the structure can be simplified.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is an exploded perspective view of an essential part of an automobile exhaust muffler to which the present invention is applied. The overall structure is the same as that shown in the conventional example, and FIG. It corresponds to the part indicated by arrow V. FIG. 1 shows a metal inner pipe 1 for passing exhaust gas and a rear joint pipe 2 that supports a rear end portion as one end portion of the inner pipe 1.

The rear joint pipe 2 is fitted to a rear boss portion formed on the rear end wall of the outer shell as shown in the conventional example, and joins the upper and lower outer shell members of the outer shell to each other. Further, as shown in FIG. 2 showing the assembled state of the inner pipe 1 and the rear joint pipe 2, since the glass wool mat 3 is entirely provided on the inner peripheral surface of the rear joint pipe 2, it is made of synthetic resin. Heat transfer from the inner pipe 1 to the outer shell can be prevented.

As shown in FIGS. 1 and 2, on the outer peripheral surface of the rear end portion of the inner pipe 2, a pair of rolling element guide means is provided which is recessed along the axial direction at symmetrical positions in the diametrical direction. Inner ball support grooves 4 are provided so as to extend parallel to each other. Each of the inner ball support grooves 4 receives a part of a steel ball 5 as a rolling element.

A large diameter portion 2a which can be fitted into the rear boss portion is formed at one end portion in the axial direction of the rear joint pipe 2, and the other end portion is bent inward at the other end portion in the axial direction. The inner cylindrical portion 2b as the other end portion
Are formed coaxially. In the assembled state shown in FIG. 2, the inner cylindrical portion 2b surrounds the rear end portion of the inner pipe 1, and the inner peripheral surface of the inner cylindrical portion 2b is
A pair of outer ball support grooves 6 as rolling element guide means are provided at diametrically symmetrical positions so as to correspond to the inner ball support grooves 4 in the assembled state. The outer ball support groove 6 is also recessed so as to receive a part of the ball 5.

In the assembled state as shown in FIG. 2, the ball 5 is interposed so as to be sandwiched between the opposing ball supporting grooves 4 and 6. The ball 5 is indicated by an arrow A in FIG. When the inner pipe 5 is displaced in the axial direction of the rear end portion of the inner pipe 5, the inner pipe 5 is rollably received in the ball support grooves 4 and 6.
The glass wool mat 7 provided on the inner peripheral surface of the rear joint pipe 2 can prevent the exhaust gas in the outer shell from leaking out from the gap between the inner pipe 1 and the rear joint pipe 2.

In the exhaust pipe structure constructed in this manner, the inner pipe 1 expands and contracts in the direction shown by the arrow A in FIG. 2 under the influence of exhaust heat, but the rear joint pipe 2 is described above. As described above, the heat transfer is prevented by the glass wool mat 7 and the glass wool mat 7 does not expand or contract thermally, and a relative displacement occurs between both the inner pipe 1 and the rear joint pipe 2. The inner pipe 1 is supported by the rear joint pipe 2 via the balls 5 as described above, and the resistance generated between the inner pipe 1 and the rear joint pipe 2 by the movement of the balls 5 rolling in the both ball support grooves 4 and 6 is generated. Since it can be absorbed, the resistance at the time of thermal expansion and contraction of the inner pipe 1 can be suitably reduced.

Further, since the sliding contact ring made of the stainless wire shown in the conventional example is not fixed by spot welding, there is no problem of durability of the welded portion, and the durability can be further improved. Further, the simple structure enables inexpensive manufacturing.

Further, the structure of the present invention can be applied to various parts of the slide part of the exhaust pipe, and can be used for a joint part of a double pipe structure as shown in FIG. 3, for example. In FIG. 3, a double pipe is an inner pipe 1 through which exhaust gas passes.
1 and an outer pipe 12 that coaxially surrounds the inner pipe 11. The outer pipe 12
One end of the connecting pipe 13 in the axial direction is fixed to one end of the connecting pipe 13 in the axial direction.

A pair of inner ball support grooves 14, which are recessed in the same manner as in the above embodiment, are provided on the outer peripheral surface of the rear end portion on the right side of the inner pipe 11 in the drawing. A pair of outer ball support grooves 15 that are recessed as in the above embodiment are also provided on the inner peripheral surface of the portion surrounding the rear end of the pipe 11. A ball 5, which can move while rolling inside, is received between the ball support grooves 15.

Therefore, also in the second embodiment, the resistance between the inner pipe 11 in the direction shown by the arrow B and the connecting pipe 13 at the time of thermal expansion and contraction can be similarly reduced. In addition, in the second embodiment, the outer pipe 12 and the connecting pipe 13
However, since the exhaust heat is not directly transmitted to the outer pipe 12, the thermal expansion and contraction of the outer pipe 12 is small and no inconvenience occurs.

In the present embodiment, the ball support grooves are provided on both pipes, but it is sufficient if the balls can roll.
The ball support groove may be provided only on either the inner side or the outer side. Alternatively, two parallel ridges may be provided to form a groove so that the ball is received between the ridges.

[0024]

As described above, according to the present invention, when the pipe thermally expands and contracts under the influence of exhaust heat, the rolling element can move while rolling in the axial direction of the pipe end portion. The resistance during relative displacement between the pipes can be made as small as possible, and there is no need to fix the sliding contact ring that slidably supports the pipe by spot welding, which affects durability.
Since the pipe can be displaceably supported with a simple structure, the durability can be improved and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an essential part of an automobile exhaust silencer to which the present invention is applied.

FIG. 2 is an enlarged side sectional view of an essential part showing an exhaust pipe structure according to the present invention.

FIG. 3 is a diagram corresponding to FIG. 2 showing a second embodiment.

FIG. 4 is an external view of an exhaust silencer for a vehicle showing a conventional example.

FIG. 5 is an enlarged side sectional view of an essential part showing a conventional exhaust pipe structure.

[Explanation of symbols]

 1 Inner Pipe 2 Rear Joint Pipe 2a Large Diameter Part 2b Internal Cylindrical Part 3 Glass Wool Mat 4 Inner Ball Support Groove 5 Ball 6 Outer Ball Support Groove 7 Glass Wool Mat 11 Inner Pipe 12 Outer Pipe 13 Connection Pipe 14 Inner Ball Support Groove 15 Outer Ball Support Groove 21 Outer shell 21a Front boss portion 21b Rear boss portion 22 Inner pipe 23 Upper outer plate member 24 Lower outer plate member 23a / 24a mating portion 25 Front joint pipe 26 Rear joint pipe 27 Glass wool mat 28 Sliding contact ring

Claims (1)

[Claims] 1. One end portion of both pipes connected to each other is formed so as to surround the other end portion, and an outer peripheral surface of the one end portion and an inner peripheral surface of the other end portion are formed. A rolling element is interposed between the rolling elements, and rolling element guide means is provided on at least one of the both ends so as to guide the rolling elements so that they can be displaced in the axial direction of the both ends. Exhaust pipe structure.